Europium and terbium thiocyanates: Syntheses, crystal structures, luminescence and magnetic propertiesстатья
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Дата последнего поиска статьи во внешних источниках: 26 августа 2016 г.
Авторы:
Petrosyants S. ,
Dobrokhotova Z. ,
Ilyukhin A. ,
Efimov N. ,
Mikhlina Y. ,
Novotortsev V.
Журнал:
Inorganica Chimica Acta
Том:
434
Год издания:
2015
Издательство:
Elsevier BV
Местоположение издательства:
Netherlands
Первая страница:
41
Последняя страница:
50
DOI:
10.1016/j.ica.2015.05.014
Аннотация:
Thiocyanates [M(H<inf>2</inf>O)<inf>5</inf>(NCS)<inf>3</inf>]·H<inf>2</inf>O (M(III) = Eu, Tb) and Eu<inf>3</inf>(H<inf>2</inf>O)<inf>12</inf>(EtOH)<inf>3</inf>(NCS)<inf>9</inf> have been synthesized. These compounds react with 18-crown-6 to give moisture-stable polymorphous modifications of [M(18-crown-6)(NCS)<inf>3</inf>]. On transition from aqua complexes to complexes with the macrocycle, the coordination number of the complex-former increases from 8 to 9. Thermolysis of [M(H<inf>2</inf>O)<inf>5</inf>(NCS)<inf>3</inf>]·H<inf>2</inf>O in the temperature range 200-300°C revealed a principal difference in the behavior of isostructural complexes of europium and terbium. Europium thiocyanate was found to undergo a redox process. The [M(18-crown-6)(NCS)<inf>3</inf>] ensembles maintain thermal stability up to 300°C. The magnetic behavior of the [Eu(H<inf>2</inf>O)<inf>5</inf>(NCS)<inf>3</inf>]·H<inf>2</inf>O complex is determined by crystal field effects, while that of the Eu<inf>3</inf>(H<inf>2</inf>O)<inf>12</inf>(EtOH)<inf>3</inf>(NCS)<inf>9</inf> ensemble and of the compounds containing the macrocycle is mostly governed by the properties of the free Eu(III) ion. The [M(H<inf>2</inf>O)<inf>5</inf>(NCS)<inf>3</inf>]·H<inf>2</inf>O complexes manifest photoluminescence under direct excitation that is typical of Eu and Tb ions. Incorporation of the 18-crown-6 macrocycle in the complexes quenches the luminescence of REE ions completely. © 2015 Elsevier B.V. All rights reserved.
Добавил в систему:
Новоторцев Владимир Михайлович